Answer: The best long term solution to an animal problem is to fence them out of your garden using wire mesh fencing that not only goes up several feet but also extends outward at the base to prevent them tunneling underneath it. Or, you can try some of the spray on or granular repellents labeled for that animal, or try a pepper wax spray applied to the plants. You would also want to reduce nearby hiding places for them such as brush piles, weedy areas, and so on.
The following offer details on the types of fencing you would ideally erect.
I might mention that based on your description, this might be woodchuck damage. Woodchucks can be unpredictable and can inflict severe bites; if you have a woodchuck in an area where people frequent you may want to consider contacting your local animal control authority.
Good luck with your garden!
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